Solar energy collector

ABSTRACT

A solar energy collector comprised of Fresnel lenses attached by support frames to a solar tracking drive. Each of the Fresnel lenses is continuously alined with the sun during a desired period of operation and are maintained at a focus distance from energy absorbers by the support frames and the solar tracking drive. The energy absorbers may be absorption conduit.

FIELD OF THE INVENTION

This invention is in the field of solar energy systems and in particularin the field of solar energy collectors which use lenses to concentratesolar radiation for use in heat exchange applications.

BACKGROUND OF THE INVENTION

The use of lenses to concentrate solar radiation on an absorbing deviceis known in the art. Solar concentrators utilizing Fresnel lenses havealso been disclosed in the prior art. U.S. Pat. No. 5,915,376 to McLeandiscloses a solar heat collecting apparatus comprised of glass domesconsisting of Fresnel lenses. Solar radiation entering the solar heatcollecting apparatus is absorbed by an absorber plate, and transferredto a remote storage system by conventional heat transfer means.

U.S. Pat. No. 6,384,320 to Chen discloses a compound parabolicconcentrator (CPC) which is mounted under a Fresnel lens thatconcentrates the intensity of solar radiation to five to ten times abovenormal level. The focused solar radiation is further concentrated twentyto fifty times by the CPC collector. The intensified solar radiation isfocused onto the top of a stainless steel heat pipe or heat exchanger.

The use of Fresnel lenses for concentrating solar energy is disclosed inU.S. Pat. No. 6,399,874 to Olah, U.S. Pat. No. 6,299,317 to Gorthala,and U.S. Pat. Nos. 5,959,787 and 6,091,020 to Fairbanks. The devicesdisclosed in these patents provide for concentrating solar energy forphotovoltaic cells.

It is an object of the present invention to provide a simplified,economical and efficient solar collector for heat transfer applications.

It is a further object of the present invention to provide a solarcollector using a pipe for an energy absorber.

It is a further object of the present invention to provide a solarcollector that is flexible as to the intensity, distribution andgeometry of concentration of solar radiation on an energy absorber.

It is a further object of the present invention to provide a solarcollector that incorporates an energy absorber with enhanced energyabsorption efficiency.

It is a further object of the present invention to provide a solarcollector that uses a pipe with an energy retaining capsuleencapsulating the absorption zone as an energy absorber.

It is a further object of the present invention to provide a solarcollector with a simple and economical solar tracking drive.

It is a further object of the present invention to provide a solarcollector that is readily incorporated into a solar collectorinstallation that is flexible as to size and geometry.

It is a further object of the present invention to provide a simple,economical and efficient solar collector installation.

It is a further object of the present invention to provide a solarcollector installation that is simple and economical to operate andmaintain.

It is a further object of the present invention to provide a solarcollector installation that utilizes pipes as energy absorbers.

It is a further object of the present invention that provides a solarcollector and energy extraction installation that is simple andeconomical to construct, operate and maintain.

SUMMARY OF THE INVENTION

The solar energy collector of the present invention uses one or moreFresnel lenses. Typically the Fresnel lens used for the presentinvention is a extruded or molded from a thin, lightweight plastic sheetwith concentric grooves formed in one side of the lens. The grooves actas individual refracting surfaces, like small prisms when viewed incross section, bending parallel rays in a very close approximation to acommon focal length. Because the lens is thin, very little energy islost by absorption.

For a preferred embodiment, the Fresnel lenses are mounted on a supportframe above an absorption conduit which is typically a metal pipe. Ifthe Fresnel lenses are designed for a point focus or a distributed focuson an absorption zone, the absorption conduit may have an energyabsorber mounted on the conduit in the absorption zone which is enclosedin an energy retaining capsule with a high solar radiation transmissionrate and a low thermal conductivity rate, thereby providing fortransmission of the focused incident solar radiation to the absorptionzone of the energy absorber while minimizing the loss of energy from theenergy absorber to the surrounding air. An in-line or attached sphericalenergy absorber with a spherical energy retaining capsule or ahemispherical energy absorber with a hemispherical energy retainingcapsule may be used. Alternatively, a spherical or hemispherical energyretaining capsule can simply be used to encapsulate an absorption zoneon the absorption conduit. For a linear absorption zone, a cylindricalcapsule is preferred on the absorption conduit. The absorbed energy istransferred to an absorption liquid flowing through the absorptionconduit.

An absorption fin can also be incorporated inside the energy absorberwhich extends into the absorption duct and is in contact with theabsorption zone, thereby assisting in the transfer of energy to theabsorption liquid which flows through the energy absorber. Theabsorption fin would normally be made of high thermal conductivitymaterial thereby rapidly transferring the energy of the incident solarradiation from the absorption zone to the absorption liquid. A preferredmaterial for the absorption zone and absorption fins is tungsten due toits high thermal conductivity rate, its high melting point and its glassto metal sealing capabilities.

Each Fresnel lenses is mounted on a support frame which is attached to asolar tracking drive. The solar tracking drive continually aligns eachFresnel lenses with the sun, during a desired period of operation,thereby providing for continual point focus or distributed focus of theincident solar radiation on an absorption zone of the energy absorber.The absorption conduit, or other energy absorber, can be positioned sothat the Fresnel lens top surface is separated from the absorptionconduit top surface by a distance which is equal to the focal length ofthe lens, thereby providing for the incident solar radiation to befocused at a single point in the absorption zone of the energy absorberor can be positioned such that incident solar radiation is distributedon a larger area of the absorption zone. If the incident solar radiationis focused on a single point in the absorption zone of the energyabsorber, substantially higher temperatures will be experienced at thefocal point. Having the focal point coincident with the center of theenergy absorber, rather than a point on the surface of the energyabsorber, results in distribution of the energy and thereforesubstantially reduced temperatures. The focus of the incident solarradiation can be varied between the center of the absorption conduit anda point on the surface of the absorption conduit thereby varying thedistribution of the focused solar radiation and thereby the maximumtemperature experienced in the absorption zone.

Rather than a circular pattern of grooves, the Fresnel lenses may havelongitudinal grooves which result in the incident solar radiation havinga line focus rather than a single focal point. This offers an advantageof distributing the focused incident solar radiation over a larger area,thereby reducing the temperature of the absorption zone. The expandedabsorption zone for embodiments utilizing a Fresnel lens withlongitudinal grooves can be encapsulated in an energy retaining capsulewith a high solar radiation transmission rate and low thermalconductivity rate such as glass. Other portions of the absorptionconduit which do not receive focused incident solar radiation can beinsulated or merely be covered with the energy retaining capsulematerial to reduce energy loss to the surrounding air. Similarly,Fresnel lenses with oval grooves may be used to provide for distributionof energy on the absorption zone as the lens will distribute theconcentrated radiation on an expanded area rather than a single focuspoint. Further distribution of the energy can be accomplished,regardless of the pattern of grooving on the Fresnel lens, bypositioning the Fresnel lenses so that the energy absorbers haveabsorption surfaces which are displaced radially from the focal point orfocal line of the respective lenses. The extent of the distribution canbe selected based upon the desired range of surface temperatures for theabsorption zone.

The Fresnel lens itself is preferably constructed of an optically clearmaterial. These materials include but are not limited to acrylic, glass,rigid vinyl, polycarbonate, polyethylene, polyester blends including PETand PETG respectively, poly IR, polystyrene, polyurethane,polypropylene, polyacrylonitrile, Kevlar, Nomex, rubber, germanium,silicon, zinc sulfide, quartz and other such materials. The inventor'spreferred materials are polyester (PET or PETG) or a blend thereof.

A Fresnel lens can be formed or manufactured in a number of ways fromthe substrate materials identified above. This includes but is notlimited to press thermalforming, roll thermalforming, casting, embossextruding, injection molding, milling, lathing, or UV curing. Embossextrusion is the preferred method of creating Fresnel lenses. Extrudingallows for the creation of an inexpensive, thin, flat plastic sheet withan embossed Fresnel image imprinted on one side of the lens. Thepreferred materials, namely polyester (PET or PETG) can be utilized withor without protective additives. Protective additives may includeultraviolet light and antioxidant additives, both of which reduceyellowing and clouding of the Fresnel lens. These additives can beintroduced into the resin prior to the extrusion process or during theextrusion process in a step referred to a co-extruding. A protectiveco-extruded cap layer is preferred, promoting longevity of the Fresnellens.

Each Fresnel lens is secured in a focal position for focusing solarradiation passing the Fresnel lens on the absorption zone on the energyabsorber by a support frame. A preferred embodiment consists of a lensretainer to which the perimeter of the lens is attached and secured onits perimeter and a pair of pivot brackets. A preferred embodiment ofthe solar tracking drive is comprised of a base frame, a base drive, apivot rail, pivot bar, a pivot drive, a pivot drive plate, anchorpedestals and base bearings. Each of the support frames is pivotallyattached to the base frame by base pivot bearings which pivotally attachthe bottom of the pivot bracket, thereby providing for longitudinalpivoting of the support frames respectively. The longitudinal pivotingof the support frames is controlled by the pivot drive which varies theposition of the pivot bar, which is pivotally attached to the pivot railby a pivot bar bearing. The pivot rail is pivotally attached to the topof one of side of each of the solar collector support structures by topbearings.

Lateral pivoting of the solar collector support structures isaccomplished by lateral rotation of the base frame which is controlledby the base drive and facilitated by base bearings. The number of anchorpedestals and base bearings can be varied as needed to provide foradequate support and reliability. By controlling the lateral pivotingand the longitudinal pivoting of the support frames the axis of each ofthe Fresnel lenses can be maintained in alignment with the sun during adesired period of operation thereby maintaining the focus of theincident solar radiation on the desired absorption zones of each of theenergy absorbers. The base drive and the pivot drive can each becontrolled by a sensor which continually adjusts the alignment of theaxis of the Fresnel lenses to match the position of the sun in the skyduring a desired period of operation. This allows the Fresnel lenses tobe aligned with the incident solar radiation for the time of day andseason of the year.

Depending upon the material used for the Fresnel lens and the thicknessof the lens, the lens may be rigid or somewhat flexible. Because thesolar collector will generally be used in an exterior, unprotectedenvironment, the support frame and the solar tracking drive must be ableto withstand wind loading, moisture and temperature variations. Further,because of the wind and other environmental conditions to which the lenswill be subjected, it must be securely attached to the lens retainer.This can be accomplished by many attachment means known in the artincluding.

The Fresnel lens support frame as well as the solar tracking drivecomponents, can be constructed from a variety of materials including,but not limited to, steel, aluminum or plastic. A preferred material forthe support frames and the solar tracking drive is steel. Anon-corrosive coating such as galvanizing, paint or powder coating,would be needed.

The base drive and the pivot drive, which comprise the drive means ofpreferred embodiments of the solar tracking drive, can be comprised ofany of common drive mechanisms known in the art. These drive means willgenerally be composed of a combination of electric motors and gears.Chains and belts may also be used. The solar tracking can beaccomplished through simple programming to a vary the longitudinal angleand the lateral angle based on the orientation of the solar collector,the longitude and latitude of the installation, the time of day, and theday of the year. Alternatively, a sensor can be used to continuallyalign the axis of the Fresnel lenses with the incident solar radiationduring a desired period or operation.

Many variations of geometry and grooving of the Fresnel lens may beused. As discussed above, longitudinal grooving will provide fordistributed focus of the incident solar radiation on a absorptionconduit. If a spot focus is desired, then the grooving will be circular.A rectangular or square lens is more practical and economical tomanufacture and utilize and is more efficient for a normal application,since the grooving provides for the concentration of solar radiationincident to the corners of the lens on the absorption zone as well. Oneof the main advantages of the present invention is economy. Onepreferred embodiment utilizing rectangular lenses with longitudinalgrooving, providing for a distributed focus on an absorption conduit,and a solar tracking drive which is actuated by a sensor can be veryeconomical and very effective compared to other solar energy collectionsystems known in the art. Preferably, the longitudinal axis of the solarcollector installation will be aligned in an east/west direction and thelateral axis will be aligned in a north/south direction.

One or more absorption liquid pumps typically circulate the absorptionliquid through absorption liquid lines to the absorption conduit andback to an energy transfer device which can be one or more of a numberof energy exchange devices which are known in the art. A variety ofabsorption liquids may be used for circulating through the absorptionconduits, which include but are not limited to water, oil or salt.Absorption liquids preferred by the present inventor are heat transferoil for lower temperatures and molten salt for higher temperatureabsorption liquid applications. Salt materials which work well for hightemperature applications include sodium nitrate, sodium nitrite orpotassium nitrate. Heat transfer oil can be synthetic, organic or acombination of synthetic and organic oil.

A preferred embodiment of an energy transfer system comprises the energytransfer device, transfer liquid circulation lines and transfer liquidpumps. Transfer liquid is circulated through the transfer liquidcirculation lines by the transfer liquid pumps to the energy transferdevice and back to an energy extraction device such as a steam turbineengine. Again, any number of liquids may be used for the transfer liquidbut to eliminate the necessity of another heat exchange process at theenergy extraction device, water is preferred. The steam turbine engineillustrated in FIG. 10 is disclosed in U.S. Pat. No. 6,533,539 toJohnson, the inventor of the present invention and provides for theflashing of heated water or other liquids from peripheral nozzles. Theenergy extracted by the energy extraction device, such as the steamturbine illustrated, can be used to drive a generator or other energyconversion device. Make up water can be supplied through a make up waterline which is controlled by an automated valve or pump connected to amake up water supply.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal vertical cross section of an embodiment of asolar energy collector of the present invention.

FIG. 2 is a plan view of a Fresnel lens with longitudinal grooves for asolar collector with a linear absorption zone.

FIG. 3 is a side perspective view of a solar energy collectorinstallation of the present invention with an absorption conduit havinga spherical energy absorber in a spherical energy retaining capsule.

FIG. 4 is a side perspective view of a multiple solar energy collectorinstallation of the present invention with support frames, absorptionconduit, and solar tracking drive.

FIG. 5 is a perspective detail of an embodiment of a solar trackingdrive of the present invention.

FIG. 6 is a perspective detail of an embodiment of a solar energycollector installation of the present invention with secondary lens,secondary lens frame and an in-line half spherical energy absorber witha half spherical energy retaining capsule.

FIG. 7 is a cutaway detail of an in-line half spherical energy absorberof the present invention with a half spherical energy retaining capsule.

FIG. 8 is a plan view cross section of an in-line half spherical energyabsorber of the present invention with absorption fins and a halfspherical energy retaining capsule.

FIG. 9 is a vertical cross section of an in-line half spherical energyabsorber of the present invention with absorption fins and a halfspherical energy retaining capsule.

FIG. 10 is an isometric illustration of an embodiment of the solarenergy collector installation, energy exchange system, and turbineengine of the present invention.

DETAILED DESCRIPTION

Referring first to FIG. 1 a cross section of a Fresnel lens 3 and energyabsorber 5 components of a solar energy collector 1 of the presentinvention. The energy absorber as shown is an absorption conduit 7 whichhas an internal absorption fin 9 extending into an absorption duct 10,which for an absorption conduit is merely the internal barrel of thepipe. The Fresnel lens axis 11 is aligned with the incident solarradiation 13. This results in the incident solar radiation being focusedto a focal point 15 as is illustrated by the incident rays 17 and thefocused rays 19. The energy absorber, which for the embodiment shown inFIG. 1, is an absorption conduit, will have an absorption zone 21 on thetop surface of the absorption conduit. The absorption conduit willpreferably be positioned so that the center 23 of the absorption conduitis aligned with the Fresnel lens axis. The absorption conduit, or otherenergy absorber, can be positioned so that the Fresnel lens top surface25 is separated from the absorption conduit top surface 27 by a distance29 which is equal to the focal length of the lens as shown in FIG. 1,thereby providing for the incident solar radiation to be focused at asingle point in the absorption zone of the energy absorber or can bepositioned such that incident solar radiation is distributed on a largerarea of the absorption zone. If the incident solar radiation is focusedon a single point in the absorption zone of the energy absorber,substantially higher temperatures will be experienced at the focalpoint. Having the focal point coincident with the center of the energyabsorber, rather than a point on the surface of the energy absorber,results in substantially reduced temperatures. Of course the focus ofthe incident solar radiation can be varied between the center of theabsorption conduit and a point on the surface of the absorption conduitthereby varying the distribution of the focused solar radiation andthereby the maximum temperature experienced in the absorption zone. Anabsorption fin 9 can also be incorporated inside the energy absorberwhich extends into the absorption duct 10 as shown FIG. 1 and shown inFIGS. 8 and 9 is in contact with the absorption zone, thereby assistingin the transfer of energy to the absorption liquid 33 which flowsthrough the energy absorber. The absorption fin would normally be madeof high thermal conductivity material thereby rapidly transferring theenergy of the incident solar radiation from the absorption zone to theabsorption liquid. An energy retaining capsule 35 can be used toencapsulate the absorption zone. The energy retaining capsule will beconstructed of material with a high solar radiation transmission rateand a low thermal conductivity rate thereby providing for transmissionof the focused incident solar radiation to the absorption zone of theenergy absorber while minimizing the loss of energy from the energyabsorber to the surrounding air 37.

Each groove 38 of the Fresnel lens is a small piece of an asphericalsurface 39. The tilt 41 of each surface is varied with distance 42 fromthe center 43 of the lens to provide for focus of the incident solarradiation at the focal point of the lens. The cross section shown inFIG. 1 could be illustrative of a Fresnel lens with circular grooveswhich will provide for focusing of the incident solar radiation to asingle focal point or could be illustrative of a Fresnel lens withlongitudinal grooves as shown in FIG. 2.

The Fresnel lens of FIG. 2 with longitudinal grooves 44 results in theincident solar radiation being focused in a line rather than a singlefocal point. This offers an advantage of distributing the focusedincident solar radiation over a larger area, thereby reducing thetemperature of the absorption zone. The expanded absorption zone forembodiments utilizing a Fresnel lens with longitudinal grooves can beencapsulated in an energy retaining capsule with a high solar radiationtransmission rate and low thermal conductivity rate such as glass.Similarly, a Fresnel lens with oval grooves provides for distributedfocus and distribution of the concentrated energy on the energyabsorber. Also, if the Fresnel lens is positioned so that the energyabsorbers have absorption surfaces which are displaced radially from thefocal point or focal line of the respective lenses, the largerabsorption zone may be encapsulated. Other portions of the absorptionconduit which do not receive focused incident solar radiation can beinsulated or merely be covered with the energy retaining capsulematerial to reduce energy loss to the surrounding air.

A cement coating can be placed on the absorption zone to increase theabsorption rate of the focused incident solar radiation. Alternatively,an energy assimilator of high thermal conductivity material can beplaced on the absorption conduit or other energy absorber. Further theenergy assimilator can be thermally connected to an absorption finextending into the absorption duct, thereby increasing the energytransfer rate to the absorption liquid.

Material selection for the absorption zone of the energy absorber orenergy assimilator placed on the energy absorber in the absorption zonewill be selected based upon anticipated maximum temperatures and desiredabsorption and thermal conductivity rates. Materials that can be usedinclude stainless steel, carbon steel, tungsten, titanium, molybdenum,rhenium, niobium, platinum, copper and other metals and non-metallicmaterials. A preferred material for the absorption zone and absorptionfins is tungsten due to its high thermal conductivity rate, its highmelting point and its glass to metal sealing capabilities.

The energy retaining capsule 35, whether it is spherically shaped asindicated on FIG. 1 and FIG. 3, hemispherically shaped as indicated onFIG. 6 or tubularly shaped for an absorption conduit, the capsule can bemade from a number of materials including soda lime glass, borsilicateglass or quartz. Borsilicate glass is a preferred material because ofits inherent impact strength and its lower thermal conductivity rate.While a spherical or hemispherical shape is preferred for a point focusdue to a higher solar radiation transmission rate and a higherabsorption rate, other shapes can be used, depending upon the energydistribution desired on the absorption zone. For a linear absorptionzone, a cylindrical capsule is preferred on the absorption conduit.

It is preferred for the retaining capsule material to be bonded orhermetically sealed to the absorption zone or to the absorption conduit.This generally increases energy retention by the absorption conduit orother form of energy absorber. Alternatively a space may be providedbetween the energy absorber and the energy retaining capsule, whetherthe energy retaining capsule is spherically shaped, hemisphericallyshaped or cylindrically shaped, which may be air evacuated, therebyproviding a vacuum space separating the energy retaining capsule fromthe energy absorber, thereby further enhancing the energy retention ofthe energy retaining capsule.

The Fresnel lens itself is preferably constructed of an optically clearmaterial. These materials include but are not limited to acrylic, glass,rigid vinyl, polycarbonate, polyethylene, polyester blends including PETand PETG respectively, poly IR, polystyrene, polyurethane,polypropylene, polyacrylonitrile, Kevlar, Nomex, rubber, germanium,silicon, zinc sulfide, quartz and other such materials. The inventor'spreferred materials are polyester (PET or PETG) or a blend thereof.

A Fresnel lens can be formed or manufactured in a number of ways fromthe substrate materials identified above. This includes but is notlimited to press thermalforming, roll thermalforming, casting, embossextruding, injection molding, milling, lathing, or UV curing. Embossextrusion is the preferred method of creating Fresnel lenses. Extrudingallows for the creation of an inexpensive, thin, flat plastic sheet withan embossed Fresnel image imprinted on one side of the lens. Thepreferred materials, namely polyester (PET or PETG) can be utilized withor without protective additives. Protective additives may includeultraviolet light and antioxidant additives, both of which reduceyellowing and clouding of the Fresnel lens. These additives can beintroduced into the resin prior to the extrusion process or during theextrusion process in a step referred to a co-extruding. A protectiveco-extruded cap layer is preferred, promoting longevity of the Fresnellens.

Referring now to FIG. 3 and FIG. 4, a preferred embodiment of a solarenergy collection apparatus of the present invention is shown. Referringto FIG. 3 the Fresnel lens 3 is secured in a focal position 45 forfocusing solar radiation passing the Fresnel lens on the absorption zoneon the energy absorber by a support frame 47. For this embodiment thesupport frame consists of a lens retainer 49 to which the perimeter 51of the lens is attached and secured on its perimeter and a pair of pivotbrackets 53.

Referring to FIG. 4 and FIG. 5, a preferred embodiment of the solartracking drive is comprised of a longitudinal pivot means, a lateralpivot means and a tracking control means. A preferred embodiment of thelateral pivot means comprises a base frame 55, a base drive 57, anchorpedestals 67 and base bearings 69. Lateral pivoting 83 of the solarcollector support structures is accomplished by lateral rotation 85 ofthe base frame 55 through a lateral angle which is controlled by thebase drive 57 and facilitated by base bearings 69. The number of anchorpedestals and base bearings can be varied as needed to provide foradequate support and reliability.

A preferred embodiment of the longitudinal pivot means comprises a pivotrail 59, pivot bar 61, a pivot drive 63, a pivot drive plate 65, basepivot bearings 71, pivot bar bearing 77, and top bearings 81. Each ofthe support frames is pivotally attached to the base frame by the basepivot bearings 71 which pivotally attach the bottom 73 of the pivotbracket, thereby providing for longitudinal pivoting 75 of the supportframes respectively through a longitudinal angle. The longitudinalpivoting of the support frames is controlled by the pivot drive 63 whichvaries the position of the pivot bar 61, which is pivotally attached tothe pivot rail by a pivot bar bearing 77. The pivot rail is pivotallyattached to the top of one of side 79 of each of the solar collectorsupport structures by top bearings 81.

A tracking control means controls the lateral pivoting 83 and thelongitudinal pivoting 75 of the support frames so that the axis 11 ofeach of the Fresnel lenses is maintained in alignment with the sunduring a desired period of operation thereby maintaining the focus ofthe incident solar radiation on the desired absorption zones of each ofthe energy absorbers. For a preferred embodiment, the tracking controlmeans consists of a sensor which controls the base drive and the pivotdrive, thereby continually adjusting the alignment of the axis of theFresnel lenses to match the position of the sun in the sky during adesired period of operation. An alternative embodiment of the trackingcontrol means is a simple computer which controls the base drive and thepivot drive and continually positions the support frames, during adesired period of operation, based upon the physical orientation of thesolar collector installation, the date, the time of day, and thelongitude and latitude of the installation. This allows the Fresnellenses to be continually aligned with the incident solar radiation.

Referring to FIG. 4, preferably, the longitudinal axis 109 of the solarcollector installation will be aligned in an east/west direction and thelateral axis 111 will be aligned in a north/south direction.

Referring now to FIG. 6 and also FIG. 7, an in-line energy absorber 87which has a hemispherical absorption zone which is encapsulated by ahemispherical shaped energy capturing capsule 89. The energy absorber isaffixed in line in the absorption conduit 7 with the connection to theconduit 90, typically by flanged or mechanical joint connections. Forsome embodiments an optional secondary lens 91 is affixed between theFresnel lens and the energy absorber by a secondary lens frame 93 whichis affixed to the opposing pivot brackets 53 of the Fresnel lens supportframe.

Referring now to FIG. 8 and FIG. 9, an embodiment of a hemisphericalshaped energy absorber 87 with absorption fins 9 inserted in the flowpath 97 of the absorption is shown. The absorption fins facilitate thetransfer of energy from the energy absorber to the absorption liquid 33.The energy absorber is encapsulated by an energy capturing capsule 101of one of the preferred materials described above.

Depending upon the material used for the Fresnel lens and the thicknessof the lens, the lens may be rigid or somewhat flexible. Because thesolar collector will generally be used in an exterior, unprotectedenvironment, the support frame 47 and the solar tracking drive must beable to withstand wind loading, moisture and temperature variations.Further, because of the wind and other environmental conditions to whichthe lens will be subjected, it must be securely attached to the lensretainer 49. This can be accomplished by many attachment means known inthe art including, but not limited to, springs, wire, bungee cords,plastic strips or ties, glue, screws, clamps or slidable inserts. Apreferred attachment means is springs. Springs allow for thermalexpansion, wind loads, hail stones or any other type of contraction orexpansion that the Fresnel lens may encounter. Referring to FIG. 2,spring receptacles 103, which, in the case of a lens formed byextrusion, may be extruded out during the extrusion process or they maybe punched or drilled in the perimeter 105 of the lens. Spring grommets107 may be inserted into the spring receptacles if needed for addedstrength and durability. One end of the spring is inserted in the springreceptacle and the other end is attached to the lens retainer or otherpoint on the support frame.

Referring to FIGS. 3, 4 and 5, pivot bearings can be any variationsknown in the art. Pivot bearings can be manufactured from a number oftypes of commonly used material including, but not limited to, steel,graphite, plastic or ceramic. A preferred pivot bearing is a steel metalsleeve bearing. The base bearings 69 can also be steel metal sleevebearings or a ceramic pipe, tube or sleeve bearing can be used as a heatbarrier. Base frame bearings can be used as a thermal barrier betweenthe support frame and the absorption conduit.

The Fresnel lens support frame 47 as well as the solar tracking drivecomponents, can be constructed from a variety of materials including,but not limited to, steel, aluminum or plastic. A preferred material forthe support frames and the solar tracking drive is steel. Anon-corrosive coating such as galvanizing, paint or powder coating,would be needed.

Referring to FIG. 5, the base drive 57 and the pivot drive 63, whichcomprise the drive means of the solar tracking drive can be comprised ofany of common drive mechanisms known in the art. These drive means maybe comprised of a combination of electric motors and gears or may bepneumatically or hydraulically actuated. If the base drive and the pivotdrive are pneumatically or hydraulically actuated, solar tracking willordinarily be accomplished through the use of pneumatic or hydrauliccylinders. Chains and belts may also be used with electric motor drives.

The solar tracking can be accomplished through simple programming to avaried longitudinal angle 75 and the lateral angle 83 based on thelongitude and latitude of the installation, the time of day, and the dayof the year. Alternatively, the sensor can be used to continually alignthe axis of the Fresnel lenses with the incident solar radiation duringa desired period or operation.

Many variations of geometry and grooving of the Fresnel lens may beused. As discussed above, longitudinal grooving as shown in FIG. 2 willprovide for distributed focus of the incident solar radiation on aabsorption conduit. If spot focus is desired so the solar energy can beconcentrated to energy absorbers such as shown in FIGS. 6, 7, 8 and 9,then the grooving will be circular. A rectangular or square lens is morepractical and economical to manufacture and utilize and is moreefficient for a normal application, since the grooving provides for theconcentration of solar radiation incident to the corners of the lens onthe absorption zone as well.

One of the main advantages of the present invention is economy. Onepreferred embodiment utilizing rectangular lenses with longitudinalgrooving, providing for a distributed focus on an absorption conduit,and a solar tracking drive which is actuated by a sensor can be veryeconomical and very effective compared to other solar energy collectionsystems known in the art.

Referring now to FIG. 10, a schematic of an energy production system 113utilizing the solar energy collector 1 of the present invention shown.The incident solar radiation 17 focused on the absorption conduit 7 byone or more solar collectors, each utilizing a Fresnel lens 3 and asupport frame (not shown) and being positioned by a solar tracking drive(not shown). One or more absorption liquid pumps 115 circulate theabsorption liquid 33 through absorption liquids lines 117 to theabsorption conduit and back to an energy transfer device 119 which canbe one or more of a number of energy exchange devices which are known inthe art.

A variety of absorption liquids may be used for circulating through theabsorption conduits, which include but are not limited to water, oil orsalt. Absorption liquids preferred by the present inventor are heattransfer oil for lower temperatures and molten salt for highertemperature absorption liquid applications. Salt materials which workwell for high temperature applications include sodium nitrate, sodiumnitrite or potassium nitrate. Heat transfer oil can be synthetic,organic or a combination of synthetic and organic oil.

Transfer liquid 121 is circulated through transfer liquid circulationlines 123 by transfer liquid pumps 125 through the energy transferdevice 119 and back to an energy extraction device 127 such as the steamturbine engine 129 illustrated in FIG. 10. Again, any number of liquidsmay be used for the transfer liquid but to eliminate the necessity ofanother heat exchange process at the energy extraction device, water ispreferred. A preferred steam turbine engine for incorporation with thesolar collector installation of the present invention as illustrated inFIG. 10 is disclosed in U.S. Pat. No. 6,533,539 to Johnson, the inventorof the present invention and provides for the flashing of heated wateror other liquids from peripheral nozzles. The energy extracted by theenergy extraction device, such as the steam turbine illustrated, can beused to drive a generator or other energy conversion device. Make upwater 131 can be supplied through a make up water line 133 which iscontrolled by an automated valve or pump 135 connected to a make upwater supply 137.

Other objects, features and advantages of the present invention willbecome apparent from the preceding detailed description considered inconnection with the accompanying drawings. It is to be understood,however, that the drawings are designed as an illustration only and notas a definition of the limits of the invention. Therefore, the foregoingis intended to be merely illustrative of the invention and the inventionis limited only by the following claims.

1. Apparatus for solar energy collection comprising: a) one or moreFresnel lenses, each Fresnel lens having a focal axis; b) one or moreenergy absorbers, each energy absorber having one or more internalabsorption ducts for transferring solar energy absorbed by the energyabsorber to an absorption liquid; c) one or more support frames, eachsupport frame securing a respective Fresnel lens in a respective focusposition for focusing solar energy passing the Fresnel lens on anabsorption zone of an energy absorber; and d) one or more solar trackingdrives affixed to the support frames for maintaining alinement of thefocal axis of each of the Fresnel lenses with the sun and maintainingeach of the Fresnel lenses in a respective focus position during adesired period of operation.
 2. Apparatus as recited in claim 1 whereinthe energy absorbers are absorption conduits.
 3. Apparatus as recited inclaim 1 further comprising an absorption liquid circulating systemconnected to the absorption ducts in each energy absorber.
 4. Apparatusas recited in claim 2 wherein each absorption zone is comprised of anenergy assimilator of high thermal conductivity material affixed to theabsorption conduit.
 5. Apparatus as recited in claim 4 wherein eachenergy assimilator is spherically shaped.
 6. Apparatus as recited inclaim 1 wherein the absorption zone of each energy absorber isencapsulated in an energy retaining capsule of material with a highsolar radiation transmission rate and a low thermal conductivity rate.7. Apparatus as recited in claim 6 wherein the energy retaining capsuleis comprised of transparent material.
 8. Apparatus as recited in claim 6wherein the energy retaining capsule is spherically shaped.
 9. Apparatusas recited in claim 7 wherein the transparent material is a borsilicateglass.
 10. Apparatus as recited in claim 3 wherein the absorption liquidcirculating system comprises an absorption liquid conduit system and oneor more absorption liquid pumps.
 11. Apparatus as recited in claim 3wherein the absorption liquid is an oil.
 12. Apparatus as recited inclaim 3 further comprising an energy transfer system connected to theabsorption liquid circulating system.
 13. Apparatus as recited in claim12 wherein the transfer liquid is water.
 14. Apparatus as recited inclaim 12 wherein the energy transfer system comprises an energyexchanger, a transfer liquid conduit system and one or more transferliquid pumps, the energy exchanger being connected to the absorptionliquid circulating system.
 15. Apparatus as recited in claim 1 whereinthe solar tracking drive comprises longitudinal pivot means, lateralpivot means and tracking control means.
 16. Apparatus as recited inclaim 1 wherein one or more of the Fresnel lenses have an elongatedfocus for an elongated absorption zone on the energy absorbers. 17.Apparatus as recited in claim 1 wherein one or more Fresnel lenses havelongitudinal grooves with a linear distributed focus for a linearelongated absorption zone on the energy absorbers.
 18. Apparatus asrecited in claim 1 wherein one or more Fresnel lenses have oval grooveswith a distributed focus for the absorption zones on the energyabsorbers.
 19. Apparatus as recited in claim 1 wherein the energyabsorbers have absorption surfaces which are displaced radially from thefocal point of the respective lenses for a distributed focus on theabsorption zones of the energy absorbers.
 20. Apparatus as recited inclaim 2 wherein the absorption conduits comprise one or more pipes. 21.Apparatus as recited in claim 1 further comprising an energy retainingcapsule with a high solar energy transmission rate and a low thermalconductivity rate encapsulating each absorption zone.
 22. Apparatus asrecited in claim 21 wherein the energy retaining capsule is spherical inshape.
 23. Apparatus as recited in claim 21 wherein the capsule is madeof borsilicate glass.
 24. Apparatus as recited in claim 2 furthercomprising a respective energy retaining capsule encapsulating eachabsorption zone on each absorption conduit.
 25. Apparatus as recited inclaim 24 wherein the energy retaining capsule comprises a conduitcoating with a high solar energy transmission rate and a low thermalconductivity rate.
 26. Apparatus as recited in claim 25 wherein theconduit coating is made of borsilicate glass.
 27. Apparatus as recitedin claim 25 wherein the conduit coating is ceramic.
 28. Apparatus asrecited in claim 1 further comprising a respective absorption finmounted in an interior absorption duct of one or more energy absorbersin the absorption zone.
 29. Apparatus as recited in claim 1 wherein oneor more of the energy absorbers comprise an energy assimilator affixedon an absorption liquid conduit.
 30. Apparatus as recited in claim 29wherein the absorption liquid conduits comprise one or more pipes. 31.Apparatus as recited in claim 30 further comprising an energy retainingcapsule with a high solar energy transmission rate and a low thermalconductivity rate encapsulating each absorption zone.
 32. Apparatus asrecited in claim 31 wherein the energy retaining capsule is spherical inshape.
 33. Apparatus as recited in claim 31 wherein the energy retainingcapsule is hemispherical in shape.
 34. Apparatus as recited in claim 31wherein the energy retaining capsule is made of borsilicate glass. 35.Apparatus as recited in claim 1 further comprising a respectiveabsorption fin mounted in an interior absorption duct of one or moreenergy absorbers at the absorption zone.
 36. Apparatus as recited inclaim 1 further comprising one or more secondary lenses affixed by asecondary lens frame to the support frame.
 37. Apparatus as recited inclaim 14 further comprising: a) steam turbine, the steam turbine havingan output shaft; and b) rotary generator affixed to the output shaft ofthe steam turbine.
 38. Apparatus for solar energy collection comprising:a) one or more Fresnel lenses for concentrating incident solar energy,each Fresnel lens having a focal axis; b) absorption means for absorbingsolar energy concentrated by the Fresnel lenses and transferring theabsorbed solar energy to an absorption liquid; c) support means forsupporting each Fresnel lens in a respective focus position for focusingsolar energy passing the Fresnel lens on the absorption means; and d)solar tracking means affixed to the support means for maintainingalinement of the focal axis of each of the Fresnel lenses with the sunand maintaining each of the Fresnel lenses in a respective focusposition during a desired period of operation.